右美托咪定对大鼠脊髓缺血再灌注损伤的影响及其机制

Effect of dexmedetomidine on spinal cord ischemia-reperfusion injury in rats

目的观察右美托咪定对大鼠脊髓缺血再灌注损伤的影响,并探讨其可能的机制。方法96只成年SD大鼠按随机数字表法分为4组（n=24）：假手术组（S组）、缺血再灌注组（IR组）、缺血再灌注右美托咪定组（DEX组）和缺血再灌注右美托咪定＋育亨宾组（DY组）,每组再分为灌注后12、24、48、72 h 4个亚组（n=6）。采用临床常用的首次负荷量加持续微量泵给药方式予以右美托咪定和育亨宾处理,并通过改良Zivin法阻断双肾间腹主动脉建立脊髓缺血再灌注损伤模型,采用BBB法对大鼠运动功能评分,HE染色观察大鼠脊髓病理学改变（L4~L6）,免疫组化观察脊髓Bax、Bcl-2表达,采用TUNEL法计数脊髓细胞凋亡率,Western blot检测Caspase3表达。结果与IR组比较,DEX组和DY组BBB运动评分升高,HE染色病理损伤明显减轻,TUNEL染色细胞凋亡率下降,免疫组化Bcl-2升高,Bax降低（P〈0.05）,Western blot显示Caspase3表达减少;与DEX组比较,DY组BBB运动评分降低,HE染色病理损伤加重,TUNEL染色细胞凋亡率升高,免疫组化Bcl-2降低,Bax升高（P〈0.05）,Western blot检测结果显示Caspase3表达增加。结论右美托咪定对大鼠脊髓缺血再灌注损伤具有明显的保护效应,其机制与激动α2肾上腺素受体,增加FAK磷酸化,并上调Bcl-2表达,下调Bax和Caspase3表达的抗细胞凋亡作用有关。

Objective To investigate the effect of dexmedetomidine on spinal cord ischemiareperfusion injury in rats,and explore possible mechanism. Methods A random number table method was used to divide 96 adult SD rats into 4 groups（ n = 24） ： sham-operation group（ S）,ischemia-reperfusion group（ IR）,dexmedetomidine treatment group（ DEX）,and dexmedetomidine and yohimbine combination treatment group（ DY）. Each group was further divided into 4 subgroups（ n = 6） according to time points（ 12,24,48 and 72 h） after ischemia-reperfusion injury. After the spinal cord ischemia-reperfusion injury model was established with an improved Zivin method,the motion function of the hind limbs was evaluated by BBB scale,and the pathological changes in L4- L6 spinal cords were observed by HE staining. The expression of Bcl-2 and Bax was examined by immunohistochemical staining,and the expression of Caspase 3 was detected by Western blotting. Meanwhile,the apoptotic rate of spinal cord cells was calculated by TUNEL assay. Results Compared with group IR,group DEX and group DY showed higher motion function scores,less pathological injury,lower expression of Bax and Caspase 3,higher expression of Bcl-2,and lower apoptotic rate（ P 0. 05）. Compared with group DY,group DEX had better outcomes in the above indexes.Conclusion Dexmedetomidine has neuroprotective effect on spinal cord ischemia-reperfusion injury through activation of α2-adrenoreceptors,phosphorylation of FAK,up-regulation of Bcl-2,and down-regulation of Bax and Caspase 3.